1. Field of the Invention
This invention is in the field of processing sugarcane bagasse into useful products.
Sugarcane stalks consist of an outer sheath-like portion composed of longitudinally extending fibers of varying lengths and a pithy center portion. The number of fibers in the stalk diminishes as the distance from the outer surface to the interior of the stalk increases. In the last decade, the cane has been genetically improved to provide a tougher stalk exterior to diminish the likelihood of penetration by boring insects (e.g., cane boring insects).
The sugarcane is cut in the field and then usually fed through a series of large crushing or milling rollers in the sugar mill to crush the stalks and extract the sugar-containing juice. The crushed, split stalks, known as bagasse, is the residue left after the juice has been extracted. The bagasse is usually piled in a field and left to decompose as a practically worthless by-product. As the bagasse leaves the last grinding mill in the sugar factory, it resembles crushed corn stalks with the individual fibers in the stalks ranging in length up to about 12 inches. The bagasse is occasionally used as a fuel for furnaces but this use is somewhat limited because of its high moisture content. Bagasse is also used sometimes as a worm bedding material by red worm growers. Since the fibers of the bagasse are quite hard, efforts to reduce the bagasse by cutting have not been successful because of cutting blade wear.
2. Description of the Prior Art
In the past, many inventors have worked on methods of processing bagasse in order to convert it into something useful. The following patents are illustrative of the prior efforts.
U.S. Pat. No. 1,876,522 to Vazquez describes a process of immersing bagasse in a solution of lime to loosen and separate the fibers. The fibers are then used in the manufacture of wall-board and paper products.
There are a number of known ways of separating the bagasse pith from the bagasse fibers. Some of these separating means are mechanical, some are chemical, while still others are a combination of mechanical and chemical separating means. Examples of the mechanical means which have been employed to separate bagasse pith from bagasse fiber can be found in U.S. Pat. Nos. 2,729,856 and 2,729,858, issued to Horton et al which describe a hammermill using water jets for processing bagasse to separate the bagasse into two portions, one which is substantially pith-free and the other which contains a major portion of the original pith. Other methods and apparatus for separating the pith from the fiber can be found in U.S. Pat. Nos. 2,723,194; 2,760,234; and 1,501,925.
U.S. Pat. No. 3,102,364 to Pullen describes transplanter pot compositions comprising bagasse pith, a cellulosic fibrous material (preferably digested bagasse fiber) and one or more of the following materials: Tillandsia usneoides (Spanish moss), a wet strength resin and a fungicide.
U.S. Pat. No. 3,163,517 to May et al discloses a method of preparing a soil conditioning composition from sugarcane bagasse which consists of weathering the bagasse, dehydrating it, classifying the weathered dehydrated bagasse, and adding inorganic plant nutrient chemicals.
U.S. Pat. No. 3,241,587 to Steele describes a hammermill-type of disintegrator for comminuting vegetal materials, such as sugarcane, by force feeding the vegetal material into the disintegrating zone, reducing the feed mass to a finely divided, substantially homogenous mass, and then extruding the mass through large apertures in a screen.
Finally, U.S. Pat. No. 3,337,326 also to May et al discloses another method of producing a soil conditioning composition consisting of compressing the sugarcane bagasse into bales, weathering the bales, comminuting the weathered bagasse, adding water to the bagasse, again weathering the bagasse in compacted piles, and adding inorganic plant nutrient chemicals.